The CHIDUSHEI CHASAM SOFER (HASHALEM) explains the claim of the woman based on the Gemara in Chulin (89a).

The Gemara in Chulin says that we see from Avraham Avinu that it is difficult to return the value of consumed stolen goods, as Avraham Avinu accepted that he would take from Sdom that which his "Nearim" -- "lads" who were with him, took after the battle. The Chasam Sofer says that the Gemara is telling us that Takanas Mei'Reish applies even to Tzadikim, like we see from Avraham Avinu. However, this woman thought that this lesson was only by Avraham Avinu who had three hundred and eighteen men helping him. It is clearly difficult to account for everything that was taken by them. However, one beam that is presently in a Sukah should not be deemed difficult to return!

However, Rav Nachman knew that the Gemara was not only teaching this lesson about many soldiers, but even about one soldier. This is because Chazal explain that the three hundred and eighteen people were actually only one person: Eliezer, whose name is the Gematria of three hundred and eighteen. Rav Nachman therefore knew that when Chazal established Takanas Me'Reish, it was for even the smallest amount of Gezel, and even for a Tzadik. This was the reason for his refusal to comply with the woman's request.

All the best,

Yaakov Montrose